Some lawn and garden tractors have traction drive systems using a continuously variable transmission (CVT) with a rubber V-belt. The rubber V-belt runs between two V-belt pulleys that are split perpendicular to their axes of rotation. The gear ratio may be changed by moving the two sheaves of one pulley closer together and the two sheaves of the other pulley farther apart. This changes the effective diameter of the pulleys, which in turn changes the gear ratio.
Lawn and garden tractor with CVTs for traction drive typically have two input controls, one for directional control and the other for speed variation. For example, a lawn and garden tractor with a CVT for traction drive may have a transmission shift lever with forward, neutral and reverse positions, and a travel pedal for speed variation. A CVT pedal control system is needed that does not also require a transmission shift lever.
Direction and speed control input forces for lawn and garden tractor CVTs may be significantly higher than those control input forces are on comparable hydrostatic and mechanical transmissions. For example, higher input forces are needed to compress the sheaves to increase speed. It may be difficult to get input forces high enough to shift a CVT through the full range of speed variation when the lawn and garden tractor is in a static state and the sheaves are not turning. A CVT pedal control system is needed that provides higher input forces than conventional pedal controls. Additionally, transmission linkages between the input controls and CVT may be subject to high input forces, and there is a need for a CVT pedal control system that can limit the forces that could damage transmission linkages and components, and that also can be used with hydrostatic and mechanical transmissions on lawn and garden tractors.